Nutrition Chapter 12
Process of copper absorption and transport:
1) high levels of dietary zinc stimulate the synthesis of metallothionein 2) Metallotheonein preferentially binds copper, limiting its absorption 3) The copper bound to metallothionein is lost when the mucosal cell dies
Why must copper be bound for transport?
Because free copper in blood would lead to oxidation and cellular damage
Iron is needed to do what?
Carry oxygen to body cells (hemoglobin) and store oxygen within cells (myoglobin)
how does chromium affect blood glucose levels?
Chromium decreases blood glucose
Those with a genetic defect in zinc absorption (acrodermatitis enteropathica) can survive well when supplemented with very large doses of zinc, but it puts them at risk for what?
Copper deficiency
What are the benefits and risks of iron supplements?
CLAIMS: Increases energy ACTUAL Benefits or Risks: Needed to make hemoglobin to deliver oxygen to tissues Supplements = beneficial if Fe is deficient High doses can cause constipation, liver damage & death
What are the functions of zinc?
-storage and release of insulin, mobilization of vitamin A from the liver and stabilization of cell membranes need zinc -Zinc influences hormonal regulation of cell division and growth and repair of tissues, the activity of the immune system and development of sex organs and bone
How can selenium reduce the need for vitamin E?
by reducing free radical formation
What can interactions among minerals affect?
trace mineral absorption -a deficiency of copper can reduce iron absorption and transport
Symptoms of iron deficiency
fatigue, headache, decreased work capacity, inability to maintain body temperature in cold environment, decreased resistance to infection.
DRIs for iron is higher in?
females who are pre-menopausal and vegetarians because they are not consuming heme iron from animal products
The most common sources of fluoride:
fluoridated water, tea, marine fish eaten with their bones (canned salmon or sardines), toothpaste
Academy of Pediatrics recommends what?
fluoride supplementation for infants.
Excessive fluoride ingestion can result in condition called:
fluorosis. Chronic ingestion of toothpaste containing fluoride can result in this condition.
This enzyme neutralizes peroxides so they cannot form what?
free radicals and this reduces need for vitamin E, which neutralizes free radicals once they have formed.
When iron needs are greater, more iron is transferred from where to where?
from ferritin to transferrin and moves into the blood
Substances that interfere with the utilization of iodine or with the function of the thyroid gland are called:
goitrogens
The BEST plant sources of selenium are
grains
Zinc is essential in the diet for what?
growth and development
Why are women of reproductive age, infants, children, and adolescents at risk for iron deficiency?
growth and increased needs
What is the iron from animal products?
heme iron
Myoglobin in red meat provides what?
heme iron and gives the meat its red color
Tooth enamel is more resistant to what?
to acid that causes tooth decay when fluoride as been incorporated.
Excess zinc can be
toxic
UL for iodine
1100 micrograms of iodine per day
UL for iron
45mg/day
What percent of dietary iron in western countries does heme iron account for?
5-10%
It is estimated that what percent o the worlds population may be iron deficient and what percent suffer from iron deficiency anemia?
80%, 30%
Fluoride is absorbed into body in proportion to the content in diet up to about what percent?
80-90%
What are the required amounts for the trace elements?
< 100 mg per day
Why might copper deficiency lead to anemia?
Copper-containing proteins are required for iron transport
Selenium absorption is efficient and homeostasis is regulated by what?
Excretion in the urine
Copper-containing ceruloplasmin converts iron to what?
Fe 3+ so iron can bind to transferrin
In hemoglobin and myoglobin, the iron ion is in what state?
Fe2+
What is the major iron storage protein?
Ferritin
The most well known selenoprotein is what?
Glutathione peroxidase
Where is iron stored bound to ferritin?
In the liver, spleen and bone marrow and to some extent in blood plasma
What affect does iodine deficiency have on the thyroid gland?
Iodine deficiency stimulates the thyroid gland to enlarge to take up iodine.
What is the function of iodine?
Iodine is an essential component of the thyroid hormones
What can result from iron poisoning?
It can be life-threatening. It can damage the intestinal lining and cause abnormalities in body pH, shock and liver failure
What is the function of iron in the body?
It is essential for delivering oxygen to cells
A disease of the heart muscle due to selenium deficiency is
Keshan disease.
Fluoride has its greatest effect on dental caries prevention during?
Maximum tooth development (early in life to 13 years)
High intakes of zinc stimulate the synthesis of _____________ in the mucosal cells
Metallothionein
How do high intakes of zinc affect copper absorption?
Metallothionein binds copper, preventing it from being released into the blood
Zinc is needed to maintain adequate levels of what?
Metallothionein proteins, which also scavenge free radicals
What is know about molybdenum?
Molybdenum in food varies with its content of the soil where the food is produced
In iodine deficiency what happens?
NO thyroid hormones are made, TSH release continues, result = GOITER
non-heme iron absorption is enhanced by what?
ascorbic acid and small amounts of meat in the diet
Iron helps carry what?
Oxygen in the blood and store oxygen in the muscle cells
Thyroid hormones promote what?
Protein synthesis and regulate basal metabolic rate, growth and development
Too much vitamin C or antacids also:
Reduce copper absorption
What trace elements are cofactors for antioxidant enzymes?
Selenium, copper, zinc, iron, and manganese
Why is bioavailability a concern for trace elements?
Small amounts in the diet can become bound to phytates, fiber, tannins, and oxalate
Fluoride is needed for what?
Strong bones and teeth
Which of the following statements is true about fluoride?
Teflon increases fluoride content of food
What is true about trace elements?
The arsenic that occurs in foods is nontoxic
Zinc can decrease what?
The bioavailability of copper
Absorption of iron is regulated at what level?
The gut level
What role does selenium have in cancer development?
The incidence of lung, prostate, and colon cancer decreased in one selenium-supplemented group
Why is bioavailability a concern with trace elements?
The interactions among minerals affect their utilization
The iodine content of food depends on what?
The soil where plants are grown or where animals graze
How do manganese, copper, and zinc influence antioxidant function?
They are required for the activity of a form of superoxide dismutase.
How are selenium and vitamin E related?
They help protect cells from oxidative damage
Iodine is needed to make what?
Thyroid hormones
Which of the following is true regarding iron absorption and transport in the body?
Transferrin transports iron from mucosal cells of the small intestine into the bloodstream.
What is iron deficiency anemia?
When there is insufficient hemoglobin red blood cells are microcyctic and hypochromic and unable to deliver sufficient oxygen to the tissues
What is the role of zinc in gene expression?
Zinc stimulates the production of metallothionein by binding to a regulatory factor.
The most common cause of iron overload is
a genetic predisposition.
Iron toxicity can also occur acutely with what?
a single large dose
What do the trace elements provide?
a variety of essential structural and regulatory roles
Which is NOT a factor in determining the rates of iron absorption?
a)Blood glucose levels b)Levels of iron stores c)Presence of vitamin C in foods d)Form of iron ingested Answer: a
With less zinc intake,
less zinc is lost when mucosal cell dies
The amount of copper typically consumed in U.S. diet is?
above the RDA
Most toxicity problems have come from people consuming what?
acidic foods or drinks that have been stored in copper containers or if the water supply is contaminated.
Intakes above the RDA, however, in individuals who are not selenium deficient will not provide;
additional benefits.
The iron from the iron-transferrin complex (in blood plasma) is taken up by cells after what?
after first binding to transferrin receptors
once absorbes, copper binds to what?
albumin, and travels to the liver where it binds to the protein ceruloplasmin for delivery to other tissues
Fluoride is present in small amounts in what?
almost all soil, water, plants, and animals
Manganese-requiring enzymes are involved in what?
amino acid, carbohydrate and cholesterol metabolism, cartilage formation, urea synthesis and antioxidant protection.
Selenium functions in association with proteins known as selenoproteins with selenium as a part what?
an amino acid selenocysteine
Iron stores that are higher than normal but not at a toxic level may be associated with:
an increased risk of cancer and heart disease
Copper deficiency not common, but most often manifests as what?
anemia because iron cannot be transported by transferrin.
Selenium plays an important role in the body's
antioxidant defenses
Who has higher needs because of iron losses due to prolonged training?
athletes
why are refined carbohydrates poor sources of chromium?
because chromium is lost in processing
Why was salt selected as a vehicle for added iodine?
because it is a food item consistently consumed by majority of the population at risk. It can be added to salt uniformly, inexpensively, and in a form well utilized by the body
why are copper deficiency symptoms are similar to those of vitamin C deficiency and scurvy?
because the enzyme needed for cross-linking of collagen for bone matrix requires copper
Copper is excreted through what?
bile and feces
What contributes to the loss of iron?
blood loss
Manganese homeostasis is regulated by absorption and excretion:
low intake = higher absorption and less excretion
Fluoride has a high affinity for what?
calcium and so is associated with calcified tissue such as bones and teeth.
How can iron overload happen?
can happen over time as iron accumulates in tissues such as the heart and the liver
Chromium is involved in what?
carbohydrate and lipid metabolism
One of the chief functions of chromium is participation in the metabolism of
carbohydrates.
Copper may be important in helping to prevent what?
certain types of anemia
cooking in stainless steel can increase food's what?
chromium content
Iodine also comes in our diet from what?
contaminants and additives in food. › Dairy products may contain iodine because of iodine-containing additives used in cattle feed and the use of iodine-containing disinfectants on cows, milking machines and storage tanks. › Iodine-containing sterilizing agents are also used in food service establishments, and iodine is used in dough conditioners and some food colorings.
Tom has an ulcer and regularly takes antacids. The absorption of which trace mineral is likely affected?
copper
Too much zinc interferes with absorption of what?
copper and impairs function of copper-zinc superoxide dismutase
Elevated blood cholesterol has been reported with what?
copper deficiency
Iodine deficiency during pregnancy may result in what?
cretinism in offspring. Cretinism results in stunted growth and poor mental development.
Other symptoms of copper deficiency:
degeneration of heart muscle, nervous system, changes in hair color and structure, impaired growth and immune function.
Fluoride is important for:
dental health
Goiter=
enlargement of the thyroid gland
Selenium supplements are marketed with claims that they will protect against what?
environmental pollutants, prevent cancer and heart disease, slow the aging process, and improve immune function.
Iodine was one of the first if not the first mineral recognized as what?
essential for man and animals
People with Wilson's Disease have a problem with what?
excretion of copper and copper accumulates. › Supplemental zinc acetate prevents copper absorption and is a good treatment for Wilson's Disease.
Zinc transport proteins:
export zinc to the lumen when zinc intake is high
What is the most common form of iron overload?
hemochromatosis- this is an inherited condition and is the most common genetic disorder in caucasians -People with this condition absorb iron better than others -these individuals may need to consume less iron and also need blood withdrawal
Most of the iron in the body is part of what?
hemoglobin
What is the iron-containing component of the blood?
hemoglobin
When iron is deficient, what cannot be produced?
hemoglobin
Iron functions as part of what?
hemoglobin and myoglobin. These molecules are important for their oxygen-carrying or oxygen-holding capacity
Copper absorption is also decreased by:
high iron, manganese and molybdenum
There may be a connection, between diets low in selenium and what?
higher incidences of cancer
Zinc supplements are often marketed to improve what?
immune function and enhance fertility and sexual performance, but are not effective if the person consuming them is not deficient in zinc.
Symptoms of (rare) chromium deficiency
impaired glucose tolerance with diabetes-like symptoms, elevated blood glucose and increased insulin levels.
Dietary sources of chromium
include brewer's yeast, liver, nuts and whole grains
When the nee for iron is greater, the percent of iron absorbed will increase or decrease?
increase
Goiter from excessive iodine can occur if?
iodine intake increases dramatically.
Soil near the ocean or sea is higher in what?
iodine than soil inland
Most of the iodine in the diet comes from what?
iodized salt (100 μg/g of salt). Iodized salt is salt fortified with iodine. "Natural" sea salt may be very low in iodine.
What is the trace mineral most likely to be under consumed on a word-wide basis?
iron
what is one of the most common types of childhood poisoning?
iron overdose due to consumption of iron-containing supplements
Levels of ferritin in blood give an indication of what?
iron stores
what are the trace elements?
iron, zinc, copper, manganese, selenium, iodine, fluoride, chromium and molybdenum.
Functions of trace mineral: molybdenum
is required as a cofactor for a number of enzymes, participates in the metabolism of the sulfur-containing amino acids and nitrogen-containing compounds in DNA and RNA, is involved in the production of uric acid and the detoxification of various compounds.
without chromium, more what is required?
more insulin
where are trace element deficiencies?
more likely in areas of the world where people eat only locally grown foods
High zinc intake promotes increased metallothionein which:
more tightly binds copper and reduces its absorption
Grain products leavened with yeast provide what?
more zinc because the yeast leavening reduces the phytate content
With high zinc intake,
more zinc is lost when mucosal cell dies
Symptoms of selenium deficiency include:
muscular discomfort and weakness.
Symptoms of selenium toxicity:
nausea, diarrhea, abdominal pain, fingernail and hair changes, nervous system abnormalities, fatigue, and irritability.
Superoxide dismutase (SOD)
needs zinc (vital for protecting cells from free radical damage)
Iron cookware can be a source of what?
non-heme iron in the diet
Heme iron is more efficiently absorbed than
nonheme iron
What is iron from plant products?
nonheme iron
Food sources of copper:
organ meats, kidney and liver, seafood, chocolate, nuts, seeds and whole-grain foods.
Fluoride supplements may help prevent what?
osteoporosis
Zinc is involved in the functioning of how many different enzymes?
over 300, including superoxide dismutase, important for protecting cells from free radical damage
Several selenoproteins are enzymes that protect cells from what?
oxidative damage
Iron is essential for the delivery of what?
oxygen to cells. Two oxygen containing proteins, hemoglobin and myoglobin contain iron
Zinc bound by what can not be absorbed?
phytates
Zinc from animal sources is better absorbed than zinc from what?
plant sources
Deficiency symptoms includes
poor growth and development, skin rashes, hair loss, diarrhea, neurological changes, impaired reproduction, skeletal abnormalities and reduced immune function.
Zinc is abundant in what food?
red meat, liver, eggs, dairy products, vegetables, and some seafood
zinc is lost from what?
refined grains during processing and is not added back
Which of the following is the richest source of iodine?
seafood
Manganese is eliminated by what?
secretion into bile
Copper is needed for synthesis of what?
several blood-clotting factors
What can be low or high in various trace minerals?
soils - This is not usually a problem with modern transportation systems because we consume food from all over the country and the world
When ferritin concentrations in the liver become high and exceed storage capacity, what happens?
some is converted to an insoluble storage protein called hemosiderin
Manganese, like copper and zinc, is needed for the activity of a form of what?
superoxide dismutase located inside mitochondria.
Which of the following is thought to be a function of silicon?
synthesis of collagen
Calcium rich food reduce what?
the bioavailability of fluoride
Consuming diets with foods high in goitrogens, such as turnips, rutabaga, cabbage, cassava and millet, limits what?
the bioavailability of iodine
The soil content affect what?
the copper in plant foods
Excess zinc impairs what?
the immune system and lowers HDL
Where is iron from the diet absorbed into?
the intestinal mucosal cells
When the supply of iodine is adequate, the body can produce what?
the needed thyroid hormones
Zinc fingers allow nuclear receptor proteins that bind to Vitamin A to interact with what?
the regulatory region of a gene and thus affect gene expression
More than half of the iodine in the body is found where?
thyroid gland
Iodine is an essential component of what?
thyroid hormone, including thyroxine
What is an iron transport protein in the blood?
transferritin
Hematocrit=
volume of red blood cells in blood
The best sources of manganese are what?
whole grains and nuts
Which of the following foods is the best source of manganese?
whole grains
What is the most abundant intracellular trace element?
zinc
What are the functions of copper?
› Iron and lipid metabolism › Connective tissue synthesis › Maintenance of heart muscle › Immune and central nervous system function › Essential component of superoxide dismutase
what are the functions of Iron?
› Is part of several proteins in the Citric Acid Cycle › Is a component of the electron transport chain (cytochromes) › Participates in drug metabolism › Enhances immune function › Is part of an enzyme catalase (destroys hydrogen peroxide before it can form free radicals)
